For example, in semiconductor manufacturing processes, existence of foreign matters (particles) or defects (hereinafter, referred to as defects, which include foreign matters and pattern defects) on a semiconductor substrate (wafer) causes incomplete insulation between wires and other failures such as short-circuit and the like. Further, along with miniaturization of circuit patterns, finer defects cause incomplete insulation of capacitors and destruction of gate oxide films. These defects come from various causes including ones occurring from moving parts of a transportation apparatuses, ones emitted from human bodies, ones generated by reaction of process gas in processing apparatuses, ones mixed in chemicals and materials, and others, and are mixed in various states. Accordingly, it is necessary to detect defects occurring in the manufacturing processes, pinpoint the occurring source of defects, and prevent defects from being outflowing.
In the prior art, as the method for finding out the causes of defects, a method has been employed where the defect position is first identified by a defect inspection system, and the defect concerned is reviewed in detail by use of a SEM (Scanning Electron Microscope) and the like and classified, and compared with the database and the cause of the defect is estimated.
Herein, the defect inspection system includes: an optical particle inspection system that implements dark-field illumination on the surface of a semiconductor substrate by a laser beam, detects scattering light from a defect, and identifies the defect position; and an optical visual inspection system or a SEM inspection system with a lamp light or a laser beam or an electron ray as its illumination light, which detects a light-field optical image of a semiconductor substrate, compares this with reference information and thereby identifies the defect position on semiconductor substrate.
These reviewing methods are disclosed in Japanese Patent Application Laid-Open Publication No. 2001-133417, Japanese Patent Application Laid-Open Publication No. 2003-7243, Japanese Patent Application Laid-Open Publication No. 5-41194, and Japanese Patent Application Laid-Open Publication No. 2005-156537.
Meanwhile, when a defect of the semiconductor substrate is to be detected by use of the optical particle inspection system, in order to increase the throughput of the inspection, the semiconductor substrate is scanned by a laser beam of a large spot size for detection. For this reason, the precision of the detect position obtained from the spot position of the laser beam that scans the semiconductor substrate will include large error components.
When a defect is reviewed in detail by the SEM on the basis of the position information of the defect including such error components, there is a case where reviewing is made with a further higher magnification (=small viewing field) than the magnification of the optical system of the optical particle inspection system, and accordingly, the defect to be reviewed may not come into the viewing field of the SEM. In order to make the detect of the reviewed object come into the viewing field of the SEM, the detect is searched for while the viewing field of the SEM is moved, but the viewing field is small, therefore, it takes much time. And consequently, the throughput of the SEM reviewing declines, and it take much time to analyze the defect, which is a problem.
In order to solve the above problem, in the Japanese Patent Application Laid-Open Publication No. 2001-133417, Japanese Patent Application Laid-Open Publication No. 2003-7243, Japanese Patent Application Laid-Open Publication No. 5-41194, and Japanese Patent Application Laid-Open Publication No. 2005-156537 mentioned previously, a parallel arrangement of the SEM and an optical microscope is disclosed. However, in order to detect defects precisely by the optical microscope, it is necessary to focus the optical microscope, but when a stage is employed so as to move up and down the semiconductor substrate for focusing, a movement stage in the vertical direction is additionally arranged to a stage that can move in the horizontal direction at a high speed and with high precision, the apparatus will become expensive and massive, which is another problem.